After update to ios 15.6 my battery health dropped 2 percent what should i do now!!

Batteries degrade over time with usage, that's just how they work.

You can expect about a 1% drop per month with average use on an iPhone.

Apple recommends replacing it when it reaches 80%.

Why lithium batteries degrade over time.

https://airqualitynews.com/2021/01/12/why-do-lithium-ion-batteries-degrade-over-time/#:~:text=These%20are%20often%20lost%20through,be%20achieved%20by%20the%20battery.

Here are some tips on maximizing battery life.

Batteries - Maximizing Performance - Apple Batteries - Maximizing Performance - Apple

You should not be concerned. Dropping battery health is entirely normal. Batteries are degradable products that will wear out with Time and charging cycles. For more reference, see this user tip I wrote about this particular topic

About battery health on your iPhone - Apple Community

I would not be concerned at all.